The fungal phytochrome FphA from Aspergillus nidulans.
The red light-sensing photoreceptor FphA from Aspergillus nidulans is involved in the regulation of developmental processes in response to light. Here we present extended biochemical and spectroscopic characterization of recombinant FphA using a synthetic gene with host-adapted codon usage. The recombinant photosensory domain FphAN753 was shown to display all features of a bona fide phytochrome. It covalently binds biliverdin as chromophore and undergoes red/far-red light-inducible photoconversion with both parent states being protonated. The large N-terminal variable extension of FphA exerts a stabilizing effect on the active Pfr state. Upon substitution of the highly conserved histidine 504, involved in the hydrogen-bonding network of the protein moiety and the chromophore, chromophore attachment and photoreversibility were completely impaired. FphA is a functional sensor histidine kinase with a strong red-light-dependent autophosphorylation activity. Furthermore, intermolecular trans-phosphorylation to the response regulator domain of a second monomer could be demonstrated. Interestingly, co-incubation of FphA and FphA variants led to enhanced autophosphorylation, including the "inactive" Pr form. The latter observed phenomenon might suggest that auto- and trans-phosphorylation activity is modulated by additional interaction partners leading to variable phosphorylation events that trigger a specific output response.
Brandt
Sonja
S
Physiologie der Mikroorganismen, Ruhr-Universität Bochum, Universitätsstrasse 150, Bochum D-44780, Germany.
von Stetten
David
D
Günther
Mina
M
Hildebrandt
Peter
P
Frankenberg-Dinkel
Nicole
N
D001233:Aspergillus nidulans / Q000378:metabolism*; D001664:Biliverdine / Q000737:chemistry; D034301:Deinococcus / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010766:Phosphorylation; D052979:Phycobiliproteins / Q000737:chemistry* / Q000502:physiology; D010834:Phytochrome / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry
D052979:Phycobiliproteins; D011994:Recombinant Proteins; D010834:Phytochrome; D006639:Histidine; D001664:Biliverdine